Reversing the size-dependence of surface plasmon resonances

Sheng Peng, Jeffrey M. McMahon, George C. Schatz, Stephen K. Gray, Yugang Sun

Research output: Contribution to journalArticle

293 Citations (Scopus)

Abstract

The size-dependence of surface plasmon resonances (SPRs) is poorly understood in the small particle limit due to complex physical/ chemical effects and uncertainties in experimental samples. In this article, we report an approach for synthesizing an ideal class of colloidal Ag nanoparticles with highly uniform morphologies and narrow size distributions. Optical measurements and theoretical analyses for particle diameters in the d ≈ 2-20 nm range are presented. The SPR absorption band exhibits an exceptional behavior: As size decreases from d ≈ 20 nm it blue-shifts but then turns over near d ≈ 12 nm and strongly red-shifts. A multilayer Mie theory model agrees well with the observations, indicating that lowered electron conductivity in the outermost atomic layer, due to chemical interactions, is the cause of the red-shift. We corroborate this picture by experimentally demonstrating precise chemical control of the SPR peak positions via ligand exchange.

Original languageEnglish
Pages (from-to)14530-14534
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number33
DOIs
Publication statusPublished - Aug 17 2010

Keywords

  • Chemical interaction
  • Extinction
  • Mie theory
  • Nanoparticle
  • Sensing

ASJC Scopus subject areas

  • General

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